Ncert Solutions Chemistry Class 11th

Diamond has a crystalline lattice where each carbon atom undergoes sp³ hybridisation and linked to four other carbon atoms by using hybridised orbitals in tetrahedral fashion.  The C–C bond length is 154 pm. The structure extends in space and produces a rigid three- dimensional network of carbon atoms. It is very difficult to break extended covalent bonding and, therefore, diamond is a the hardest substance on the earth.

Graphite has layered structure in which the layers are held by van there Waals forces and distance between two layers is 340 pm. Each layer is composed of planar hexagonal rings of carbon atoms. C—C bond length within the layer is 141.5 pm. Each carbon atom in hexagonal ring undergoes sp² hybridisation and makes three sigma bonds with three neighbouring carbon atoms. Fourth electron forms a? bond. The electrons are delocalised over the whole sheet. Electrons are mobile and, therefore, graphite conducts electricity along the sheet. Graphite cleaves easily between the layers and, therefore, it is very soft and slippery. That is why graphite is used as a dry lubricant in machines running at high temperature, where oil cannot be used as a lubricant.

1.4 In order to answer the question, we need to know the balanced equation for the combustion of carbon in dioxygen/air, which can be written as:

C (s) + O₂ (g) à CO₂ (g)

(i) We can see from the above equation,

1 mole of carbon reacts with 1 mole of oxygen to produce 1 mol of carbon dioxide.

In air, combustion is complete.

Therefore, CO₂ produced from combustion of 1 mole of carbon= Molar mass of CO₂= 44 g

(ii) As only 16 g of dioxygen is available, it can combine only with 0.5 mole of carbon, i.e., dioxygen is the limiting reactant.

Hence, CO₂ produced = 22 g

Here, dioxygen acts as the limiting reagent.

(iii) Here again, dioxygen is the limiting reactant.

16 g of dioxygen can combine only with 0.5 mole of carbon (even though 2 moles of carbon are available). Therefore, the CO₂ produced again is equal to 22 g.